larby

Hi All,

I'm rebuilding my revenger 25 and it's motor at the moment and I'm looking for a little help with keeping my drive alive! I've done loads of searching but just can't find the answers i need!

The boat is a very sleek & light revenger 25, not sure of actual weight, but it's not a big boat at all, basically a ski race boat.
Engine is a 502 mag which i will be supercharging, probably about 5psi, hoping for around 550-600hp.

I'm currently running a standard bravo 1 drive. The boat raced with this drive and 420hp for the last 20 years with no probs. I'll be using her for offshore leisure and racing but I'm concerned about the drive blowing with the higher hp.

I haven't got megabucks to throw at buying a new drive or anything, so I'm looking to see what my options are to cope with 600hp. Are there mods I can do to the drive to help it cope, different gears, internals etc? I've already got a drive shower. I've got a friend who runs a machine shop who could make up and custom parts...

Many thanks in advance,

James

jeffswav

This has been covered many times before. Do a few searches and you can read about it for hours. I run 500HP with mine, I know of a lot of guys running 600HP. Take it easy on it out of the hole, keep it in the water and not in the air. Keep the RPM below 6000 (max). I run mine at 54-5500 RPM. Use a little common sense and you will be fine.

LAKE EFFECT

An XR would be best, but I understand the budget thing. Make sure the transom assembly, gimbal ring and bushings are all tight(an HP assembly would be best). Are you running hydraulic steering? Probabally should be, it takes alot of load off the gimbal and helmet, and adds a great safety margin. A better top cap is imperative on a left rotation drive, but will stabilize the whole upper gear set left or right. And good drive shower.

The Bravo drive is small but tough, and it can take alot of abuse. But with 600+ hp on a single, its not if you'll break a drive, its when.. Buy the good stuff now, or later, your choice. Good luck.

LE

t500hps

You WILL break it eventually........get on plane by slowly rolling into the throttle and don't let the boat launch off waves where the drive leaves the water and it will last awhile. Hammer it out of the hole and jump waves like a kid on a BMX bike and it won't last one summer.


BTW: good advice on upgrading the steering, etc. If your running over 65-70 mph the stress on those other parts can be huge. Hydraulic steering, etc will the boat much safer, and help the parts live alot longer.

ICDEDPPL

iTrader: (1)

I have e a 600SC..I babied a Bravo 1 and it didn`t last.. the previous owner replaced it too. I went with XZ now and having Mr. Gadgets go tru (cryo the gears etc.) it to make sure it last more than a couple of seasons.

Mr Gadgets

Larby,
I have a friend with 598" motor in a 28' Checkmate with a stock 97 B1 and he has about 600hrs on it. I rebuilt it once so far. He did wear out a set of lower gears, but nothing broke. If you drive it right it can live.
There are a lot of mods that can be done. But the main thing is to make sure the upper case is in good condition.. If they run loose, it will wear on the case and make it useless. How many hours are on the drive? Has it ever been rebuilt. If it has the thin floored gears in it.. there is a good chance you will push the floor out. But then again, my friend has not. You really dont need an XR.. I have a customer/friend with 24' Convincer Checkmate, 518", M3 Procharged motor running a B1 that I set up. Two seasons on it. One with 454 M3 and this past summer with 518", M3.. so it can be done.

Hope that helps.
Dick

larby

Hi everyone,

Thanks for all the replies, such a pain i can't respond at the time thanks to the time difference!

I'm running Imco twin ram external steering, so that shouldn't be an issue there.

I figured I'd get a lot of advice to take it easy and not jump the boat, but as i mentioned above, I'll be racing her so that's really not an option i have!

I know I'm going to blow the drive, just hoping to maybe stretch it to a season of use??I'm guessing there are no other drives i can convert to for reasonable cost which would give me the strength i need?

With the xr thing, isn't it true that the internals can be fitted into a standard bravo? Is this worth doing?

I did have a good search but most of the 7 pages i found was about inshore and lake use, not offshore racing...

Thanks again for all the help so far, it's been great, anything else much appreciated!!

Cheers, James

Griff

If you're actually racing, you better increase your budget. Stuff is going to break, whether its a regular Bravo, XZ or XR.

BTW, I had 550hp in a 5500lb boat and the Imco upper and stock Bravo lower were still going strong with 300hrs on them when I sold the boat. I didn't baby it, but I didn't abuse it either.

LAKE EFFECT

Sounds like you might be on the other side of the Alantic, so this advice might be a little more difficult and or expensive to utilize, but this is the path I took.

I had decent parts to start with, but I wanted all XR stuff on my boat. I already had upgraded to XR lowers, but wanted to upgrade my early IMCO upppers to XR also. This past spring I was able to buy a complete set of low hr XR drives for $5500. Put all the good stuff on my boat and sold the rest. I recovered over 3k back. Turned out to be pretty affordable upgrade.

As far as upgrading a std Bravo to XR, thats pricey on the uppers, upper gear sets alone are going upwards of $1800. Plus case mods to convert the lower tower to a steel one, and the new/better shafts you will need to buy. A lower upgrade is alot easier: prop shaft, carrier, new gears(or if the gears are good, you can machine the drive gear for the XR prop shaft).

IMO, to have a good, full boating season with a Bravo and some HP, learn how to work on the Bravo, or buy an extra one.. More good luck.


LE

larby

Ha ha, this is more like it!

I am indeed on the other side of the pond... I currently have two bravo drives, I was lucky to get a spare with the boat, and may be able to get a third.
My intention is to learn to work on the drive myself. I've rebuilt several engines and boats (and used to be an engineer) so that shouldn't be an issue, just need to find the right info to go by.

Here's a thought i came up with... Seems to me the most damaging situation is where revs aren't correctly matched on re-entry (over revving).
Could this be helped much by a system which holds the revs on leaving the water till the boat is back in? Has such a system ever been tried before? It'd be like getting the throttle perfect every time...?

James